The answer is that the tester can derive the target is running a Linux-based operating system, along with the specific service versions and the fact that three distinct services are active. This is correct because the `-sV` flag enables Nmap output interpretation service version OS detection, probing open ports to reveal exact software and version numbers like OpenSSH 7.4 and Apache httpd 2.4.6, while the `-O` flag performs OS fingerprinting based on network stack behavior. On the Certified Ethical Hacker CEH exam, this question tests your ability to distinguish what each Nmap flag contributes—a common trap is assuming `-sS` alone gives version details, when it only performs a SYN stealth scan. The key memory tip is to remember that `-sV` stands for “Version,” `-O` for “OS,” and `-sS` for “Stealth SYN”—together they paint a full picture of the target’s software and operating system without needing to guess.
CEH Footprinting, Reconnaissance and Scanning Practice Question
This CEH practice question tests your understanding of footprinting, reconnaissance and scanning. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A penetration tester runs `nmap -sS -sV -O -p- 192.168.1.10` and receives the following output snippet: 'PORT STATE SERVICE VERSION 22/tcp open ssh OpenSSH 7.4 80/tcp open http Apache httpd 2.4.6 443/tcp open ssl/http Apache httpd 2.4.6'. Which THREE pieces of information can the tester derive from this output? (Choose 3)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The -sV flag was used for version detection
Option B is correct because the `-sV` flag in Nmap explicitly enables version detection, which probes open ports to determine the service and version information displayed in the output (e.g., 'OpenSSH 7.4', 'Apache httpd 2.4.6'). Without `-sV`, Nmap would only report the service name based on its port mapping (e.g., 'ssh', 'http'), not the specific version numbers.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The target has a vulnerability in OpenSSH 7.4
Why it's wrong here
Nmap does not identify vulnerabilities; it only reports versions.
✓
The -sV flag was used for version detection
Why this is correct
The presence of version numbers in the output indicates -sV was used.
Related concept
Read the scenario before looking for a memorised answer.
✓
The Apache server version is 2.4.6
Why this is correct
The output explicitly shows Apache httpd 2.4.6.
Related concept
Read the scenario before looking for a memorised answer.
✗
The target is vulnerable to the Heartbleed bug
Why it's wrong here
Heartbleed affects OpenSSL, not necessarily Apache, and Nmap output does not confirm vulnerability.
✓
The target is running a Linux-based operating system
Why this is correct
The -O flag typically infers OS, and the services (OpenSSH, Apache) are common on Linux.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume version numbers automatically imply a vulnerability (like Heartbleed or an OpenSSH flaw) without recognizing that Nmap output only reports versions, not exploitability, and that Heartbleed is specific to OpenSSL, not Apache or OpenSSH.
Trap categories for this question
Command / output trap
Heartbleed affects OpenSSL, not necessarily Apache, and Nmap output does not confirm vulnerability.
Detailed technical explanation
How to think about this question
Nmap's `-sV` flag works by sending a series of probes (e.g., NULL, FIN, or application-specific payloads) to the open port and comparing the responses against a signature database (nmap-service-probes). The `-O` flag enables OS detection via TCP/IP stack fingerprinting, analyzing factors like initial TTL, window size, and DF bit; the output snippet does not show the OS guess, but the combination of OpenSSH 7.4 and Apache 2.4.6 strongly suggests a Linux distribution (e.g., RHEL/CentOS 7). In real-world scenarios, version detection is critical for prioritizing patches, but it must be paired with a vulnerability database (e.g., CVE lookup) to confirm actual risk.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the CEH exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CEH question in full detail.
Footprinting, Reconnaissance and Scanning — This question tests Footprinting, Reconnaissance and Scanning — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The -sV flag was used for version detection — Option B is correct because the `-sV` flag in Nmap explicitly enables version detection, which probes open ports to determine the service and version information displayed in the output (e.g., 'OpenSSH 7.4', 'Apache httpd 2.4.6'). Without `-sV`, Nmap would only report the service name based on its port mapping (e.g., 'ssh', 'http'), not the specific version numbers.
What should I do if I get this CEH question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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